Weirs for use in float and sink separation



Nov. 22, 1955 F. F. RIDLEY WEIRS FOR USE IN FLOAT AND SINK SEPARATION 3 Sheets-Sheet 1 Filed Aug. 1, 1950 1955 F. F. RIDLEY WE RS FOR USE IN FLOAT AND SINK SEPARATION Filed Aug. 1, 1950 3 Sheets-Sheet 2 FIGS.

Nov. 22, 1955 F. F. RIDLEY 2,7

WEIRS FOR USE IN FLOAT AND smx SEPARATIOK Filed Aug. 1, 1950 3 Sheet 3 United States WEIRS FOR USE IN FLOAT AND SINK SEPARATION This invention relates to weirs for use in float and sink separation, and is concerned with a method of removing solid floating materials from the surface of a liquid, such as the lighter floating minerals in the float and sink separation process, wherein minerals are separated in a liquid of density intermediate the material being separated. In such processes the floats may be removed by scrapers or elevators which elevate the material out of the liquid; or the materials may be removed by floating over a weir, whereby the carrying liquid floats the lighter material over the weir. The material may be assisted over the weir by paddles or other mechanical devices helping to push the floats over the weir.

In the method of floating the lighter material over a weir, the size of the pieces of material and the quantity which can be handled are governed by the quantity of liquid overflowing the weir, and when the material contains larger size pieces, or when the required throughput is great, the quantity of liquid may be unduly high.

The object of this invention is to provide means for discharging the floating material over a weir with a reduced amount of flowing liquid, and for handling large size pieces and large capacities without requiring proportionately high amounts of liquid.

According to the invention the weir crest comprises friction roller means mounted to rotate about a horizontal axis between the side walls of said tank, said axis being located so that the periphery of said roller means is in close proximity to, and the upper portion of said periphery above, the edge of said overflow end wall, continuous upwardly and uniformly inclined submerged plane surface means for causing the liquid to converge towards the surface with correspondingly increasing velocity, said surface means terminating at its upper end adjacent to and tangential with the upper face of said roller means, said roller means being adapted to be driven so that their upper face moves in the direction of discharge of the liquid and material as it approaches said roller means so that the said material reaches the latter with considerable momentum. Thus, for example, whereas material carrying pieces 6" or 7 in size might require about depth of liquid above the weir to float it over a stationary weir, with the weir according to the invention this material would be carried over the weir with only 1" or 2" depth of liquid.

The weir crest roller may have a smooth surface, or a roughened or serrated surface, or it may be rubber covered with the object of increasing the grip on the material. It may be arranged in close clearance with the discharge side of the tank, or such trough or receptacle as may be provided to receive the discharging material and liquid. The roller may be fitted in close relationship with an inclined guide plate which leads the floating material on to the roller and the discharge over the weir may be assisted by a paddle which leads the material on to the inclined plate and to the roller. As the material comes in contact with the roller the atent motion of the latter pushes the pieces over instead of allowing them to stick as they would with a weir having a stationary side if the depth of liquid above the weir were not sutficient.

A further feature of the invention is to provide an inclined endless traveling belt instead of the inclined plate. This arrangement may comprise the weir crest roller and another roller before it at a lower level than that of the weir crest roller. The travelling belt is passed over the two rollers, the upper carrying surface of the belt rising at an incline towards the crest of the weir. Thus there is provided a travelling surface leading upwardly towards the weir, so that any material which touches the belt beneath the liquid level is conveyed forwardly and upwardly over the weir, and thereby large pieces of material are readily carried over the weir with a relatively small overflow of liquid.

Alternatively to the belt, the inclined slope leading to the weir may consist of a series of revolving rollers closely spaced to guide the material forward. Stationary distance pieces may be set between the rollers to prevent smaller pieces getting between them. Either the belt or series of rollers may be operated in conjunction with a pushing device such as a rotary or reciprocating paddle or an endless push plate conveyor, to push the material forward on to the inclined slope and over the weir.

The invention will now be described by way of example with reference to the accompanying drawings.

In the said drawings:

'Fig. 1 is a semi-diagrammatic partial side elevation in section of a simple roller type weir crest.

Fig. 2 is an end view of Fig. 1.

Fig. .3 is a similar view to Fig. 1 including a fairing plate.

Fig. 4 is a side sectional elevation of a double roller form of weir.

Fig. 5 is a similar view to Fig. 4 showing a treble roller weir.

Fig. 6 is a side sectional elevation of a weir comprising an endless belt lead-in.

Fig. 7 is a cross section of a weir according to that .shown in Fig. 4 as fitted to a coal cleaning plant.

Fig. 8 is a partial side elevation to a reduced scale of the coal cleaning plant incorporating the weir of Fig. 7.

Referring more particularly to the drawings, 1 indicates tank sides between which is a transverse outflow end wall on which a weir 2 is located. 3 is a rubber covered weir crest roller arranged in close relation to the top of the weir 2 and so as to project beyond it. Rigid with the roller 3 is a sprocket wheel 4 which is driven by a belt on the outside of the tank from a driving sprocket 6. It will be seen that with the relatively shallow overflow shown the roller 3 assists larger pieces of floats than would pass over a stationary Weir crest with the same shallowness of overflow.

Fig. 3 shows the same weir as in Figs. 1 and 2 fitted with a fairing plate 7 of dihedral form up which the floats are led to the roller 3 when the separating medium is caused to flow towards the weir. A rotary paddle 8 may be combined with the weir to assist in leading in the floating material to the plate 7 and roller 3.

Fig. 4 shows an arrangement wherein an additional roller 9 is located below the level of the roller 3, it having a sprocket by which it is driven through a belt 10 from a second sprocket rigid with the roller 3. The intervening space between the rollers 3 and 9 is filled in with an adjustable guide plate 12 of T-section mounted between two side brackets 12 arranged parallel with the roller centre line, and transversely slotted for adjustmeat to and from the roller centre line. With this form any large floats are assisted on to the plate 11 by the additional roller 9 up which they are pressed by the oncoming floats and the flow of the stream of medium until they reach the upper roller 3 which gives them a final lift over the weir.

Fig. shows an arrangement having two additional rollers 13 and 14 arranged relatively closer together than in the case of the arrangement of Fig. 4. The roller 14 is driven from the roller 13 by means of a chain 15. The intervening spaces between the rollers are filled in with guide plates 16 similar to but narrower than the plate 11 of Fig. 4. The action is similar to that of Fig. 4 with the difference that the floats are given an extra lift by the roller 13 after the additional lift by the roller 14. A reciprocating paddle 17 may be provided for co-operation with the rollers and plates for further assisting the leading in of the floating material.

Fig. 6 shows an arrangement in which a lead in or lift is imparted to the floats by means of a rubber belt 18 passing over two plain rollers 19, 20 spaced apart for about the same distance as the rollers 3 and 9 of Fig. 4. This form dispenses with the guide plate and imparts a continuous lift to the floats from the time of their contact with the belt 18 to their discharge over the weir crest. 21 is a reciprocating paddle similar to the paddle 17 of Fig. 5.

Figs. 7 and 8 show a specific form of weir according to the invention and its application to a separating tank in which the sinks are conveyed out of the separating medium by a belt conveyor, and the floats and middlings conveyed by the stream of medium towards collecting weirs, according to U. S. Patent No. 2,486,682. 22 is a transverse trough arranged near the delivery end of a float and sink separation tank 23. Two weirs 24, 25 are arranged on the leading and trailing sides respectively of the trough 22, the former being of the kind described and shown with reference to Fig. 4, that is to say a weir crest roller 25, guide plate 27 and leading in roller 26 while the latter is of the single roller kind described with reference to Fig. 1 that is to say it has a single Weir crest roller 28 mounted for vertical adiustment. The bottom plate 29 of the trough 22 is extended on both sides to form fairing plates 29a and 29b, the end of the latter of which is doubled back on its self and mounted on a transverse pivoting plate 30 having segmentally slotted side plates 31 at each end. The rollers 25 and 28 are driven through an endless belt 32 from a driving sprocket 33 mounted on a shaft 34, the belt 32 passing over an idler sprocket 35 to give the necessary driving engagement on the sprocket of the single roller 28. The lead-in roller 26 is driven from the roller 25 by a short endless belt 36.

Paddles 37 and 38 mounted respectively on the shafts 34 and 39 assist the floats on to the rollers 28 and 26,

the floats being conveyed up the leading weir assemblyroller 26, plate 27 and weir crest roller 25, and the middlings up the trailing weir assembly-plate 29b and weir crest roller 28in the opposite direction to the flow of the liquid medium.

40 is the belt for separating the floats from the sinks and ultimately conveying the latter out of the tank.

The invention is of particular advantage in applying the process described in U. S. patent specification No. 2,486,682, but is adaptable to the removal of floats in other methods of float and sink separation.

I claim:

1. In combination with a float and sink separating tank having side walls and having an outflow end wall, a weir for use in discharging the floating material comprising weir crest friction roller means mounted to rotate about a horizontal axis between the side walls of said tank, said axis being located so that the periphery of said roller means is in close proximity to, and the upper portion of said periphery above, the edge of said out-flow end wall; continuous upwardly and uniformly inclined submerged plane surface means for causing the liquid to converge towards the surface with correspondingly increasing velocity, said surface means terminating at its upper end adjacent to and tangential with the upper face of said roller means, and having its lower end disposed downwardly and outwardly from said roller means; and said roller means being adapted to be driven so that its upper face moves in the direction of discharge of the liquid and material.

2. A combination according to claim 1 wherein the inclined surface means are constituted by guide plate means which are upwardly inclined towards and'tangentially disposed relatively to the upper surface of the roller means.

3. A combination according to claim 1 wherein paddle means are provided above the inclined surface means, said paddle means being adapted to be moved towards said surface means to assist the floating material along said surface means towards said roller means.

References Cited in the file of this patent UNITED STATES PATENTS 7 1,646,506 Velten Oct. 25, 1927 2,007,190 Fraser July 9, 1935 2,209,618 Vogel July 30, 1940 2,458,035 Tromp Jan. 4, 1949 2,486,682 Ridley Nov. 1, 1949 2,489,161 Scholes Nov. 22, 1949 2,603,352 Tromp July 15, 1952 FOREIGN PATENTS 617,697 France Feb. 23, 1927 661,897 Germany June 29, 1938 

1. IN COMBINATION WITH A FLOAT AND SINK SEPARATING TANK HAVING SIDE WALLS AND HAVING AN OUTFLOW END WALL, A WEIR FOR USE IN DISCHARGING THE FLOATING MATERIAL COMPRISING WEIR CREST FRICTION ROLLER MEANS MOUNTED TO ROTATE ABOUT A HORIZONTAL AXIS BETWEEN THE SIDE WALLS OF SAID TANK, SAID AXIS BEING LOCATED SO THAT THE PERIPHERY OF SAID ROLLER MEANS IS IN CLOSE PROXIMITY TO, AND THE UPPER PORTION OF SAID PERIPHERY ABOVE, THE EDGE OF SAID OUT-FLOW END WALL; CONTINUOUS UPWARDLY AND UNIFORMLY INCLINED SUBMERGED PLANE SURFACE MEANS FOR CAUSING THE LIQUID TO CONVERGE TOWARDS THE SURFACE WITH CORRESPONDINGLY INCREASING VELOCITY, SAID SURFACE MEANS TERMINATING AT ITS UPPER END ADJACENT TO AND TANGENTIAL WITH THE UPPER FACE OF SAID ROLLER MEANS, AND HAVING ITS LOWER END DISPOSED DOWNWARDLY AND OUTWARDLY FROM SAID ROLLER MEANS; AND SAID ROLLER MEANS BEING ADAPTED TO BE DRIVEN SO THAT ITS UPPER FACE MOVES IN THE DIRECTION OF DISCHARGE OF THE LIQUID AND MATERIAL. 